Implantable, subcutaneous infusion ports are designed to provide an easily accessible means to deliver medication to a body lumen or cavity such as a blood vessel. Such devices are used, for example, to deliver a predetermined amount of medication into the patient s blood vessel. They are intended for long term use. Such ports typically include an injection chamber, which is accessible, percutaneously, through a pierceable septum. The chamber is connected to a catheter, which also is subcutaneously placed and leads to the body lumen to which the medication is to be delivered. The device is designed to be implanted just beneath the skin so that the chamber may be accessed repeatedly by passing a hypodermic needle through the skin and septum.
Patients often require the infusion of more than one type of medication. The medications frequently may be incompatible. For example, mixing different, incompatible drugs may cause crystallization or occlusion of the lumen of the delivery catheter in a single chamber implantable infusion port. Additionally, blood sometimes must be withdrawn while simultaneously infusing medication. The use of a multiple chamber infusion port with a multiple lumen catheter or a plurality of catheters facilitates such simultaneous multiple uses. Typical of such chamber dual chamber vascular access ports is that shown in U.S. Pat. No. 4,692,146. That access port has an anchoring base made of a flexible biocompatible such as silicone rubber. Two separate stainless steel ports are enclosed in the base and define chambers for medication or the like. Each of the ports is formed from a number of separate parts that are separately machined and assembled. Each port has a piercable septum and a circular stop to prevent a needle from protruding too far into the chamber after puncturing the septum. The catheter that is connected to each port is provided with a metal tube inside of the catheter where the port is attached in order to prevent the needle from inadvertently puncturing the catheter and causing it to leak. Such access ports typically have a considerable number of parts and required a substantial amount of labor for their manufacture. The use of metal components increases the weight of the implantable infusion port and may be somewhat uncomfortable for the patient. Also, a device having metal components will interfere with Magnetic Resonance Imaging ("MRI"), which is often used for diagnostic procedures. There is a need, therefore, for an improved, non-metallic subcutaneously implantable multiple chamber infusion port that is of simplified, inexpensive construction.